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Rethinking HVAC: Decarbonization, Energy Efficiency, and Indoor Air Quality

Decarbonizing HVAC systems cuts emissions and boosts efficiency. Explore how sustainable HVAC tech is transforming indoor air quality.

Ava Montini

Nov 14, 2024

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In an era where climate change, energy consumption, and public health intersect, the way we design, operate, and innovate within our buildings has never been more critical. At the heart of this transformation lies the HVAC (Heating, Ventilation, and Air Conditioning) system.


Although typically hidden from sight, HVAC infrastructure plays a crucial role in energy use, indoor air quality (IAQ), and carbon emissions. A closer look reveals that HVAC systems profoundly impact a building’s functionality, environmental footprint, public health outcomes, and operational efficiency.

The Energy-Intensive Reality of HVAC Systems

HVAC systems are among the largest energy consumers in residential and commercial buildings, often responsible for a significant portion of a building’s operating costs and environmental footprint. In the United States alone, HVAC accounts for approximately 35% of a building's energy consumption, a figure that can be even higher in colder and warmer climates due to increased heating and cooling demands. According to the 2021 Global Status Report for Buildings and Construction by the GlobalABC, the buildings sector accounted for 36% of global final energy consumption and 37% of energy-related CO₂ emissions in 2020.


Historically, HVAC systems have been energy-intensive by nature, using vast amounts of power to regulate temperature and maintain air quality within a building. This often places HVAC at the center of energy-saving and decarbonization initiatives. However, balancing energy efficiency with effective indoor air quality control has proven challenging.


Ventilation, which is essential for good IAQ, typically requires large volumes of air to be exchanged, a process that consumes significant energy and raises costs. This trade-off between energy savings and IAQ improvement has long hindered the HVAC industry’s transition to sustainable practices.


The Cost of Compromised Indoor Air Quality

Indoor air quality plays a vital role in health, well-being, and productivity. Poor IAQ has been linked to respiratory diseases, allergies, and even mental fatigue, while the economic cost of inadequate IAQ often goes unmeasured. The World Health Organization estimates that air pollution contributes to more than 4 million premature deaths each year, with indoor air pollution being a significant factor. Studies indicate that improved IAQ can reduce health risks and enhance cognitive function, particularly in office and educational settings where individuals spend extended hours indoors.


A study by the Harvard T.H. Chan School of Public Health found that participants in green office environments experienced a 61% improvement in cognitive scores, while those in green+ environments with enhanced ventilation saw scores double compared to conventional settings, underscoring the link between IAQ and productivity. Improved indoor air quality also reduces absenteeism, as shown by a U.S. Environmental Protection Agency (EPA) study reporting a 10% decrease in student absences with better IAQ, and additional research indicating that increased office ventilation can reduce short-term employee absences by 35%. These findings emphasize the importance of maintaining optimal IAQ in both educational and professional settings for health and productivity.


Comparing Outdoor vs. Indoor Air Quality

While outdoor air pollution often captures public attention, indoor air pollution can pose even greater health risks, largely because people spend nearly 90% of their time indoors. Without proper ventilation and filtration, indoor spaces can accumulate pollutants over time, creating high-risk environments even in areas where outdoor air is relatively clean. Indoor pollutants, such as volatile organic compounds (VOCs) from cleaning products, chemicals from building materials, and particulate matter from HVAC systems, often reach levels that are two to five times higher than outdoor levels. Compounding this, outdoor pollution or environmental factors, like wildfire smoke or high pollen counts, can seep indoors, adding to the burden on indoor air quality if not properly managed.


Bridging the Gap Between IAQ and Energy Efficiency

The perception that energy savings and optimal IAQ are mutually exclusive has evolved with advances in HVAC technology. New systems now offer solutions that provide fresh, filtered air without excessive energy consumption. Energy-efficient HVAC systems are equipped with features like variable-speed compressors, heat exchangers, and intelligent sensors that adjust airflow based on occupancy and usage patterns, more effectively balancing IAQ and energy use.


Key Technologies Redefining IAQ and Energy Efficiency in HVAC:

  1. Variable Refrigerant Flow (VRF) Systems: These systems allow precise control over the cooling and heating of each zone within a building, reducing energy consumption by eliminating the need to heat or cool unused areas.


  2. Heat Recovery Ventilation (HRV) Systems: HRVs reclaim heat from outgoing air and transfer it to incoming air, reducing the energy required to maintain indoor temperatures.


  3. Demand-Controlled Ventilation (DCV): DCV uses sensors to monitor CO2 levels and occupancy within a space, adjusting ventilation rates dynamically. This reduces unnecessary energy use and enhances air quality by providing fresh air only when needed.


  4. Low-Pressure Advanced Filtration: Low-pressure polarized filters efficiently capture pollutants like VOCs and fine particles with minimal airflow resistance, supporting energy and operational efficiency.


  5. Smart Thermostats and Building Automation: These systems enable HVAC units to operate at optimal efficiency by learning usage patterns, predicting occupancy, and adjusting temperature and ventilation levels based on real-time data.


The Role of HVAC in Building Decarbonization

With buildings accounting for nearly 40% of global energy consumption, they play a significant role in carbon emissions. Decarbonizing HVAC systems involves reducing direct emissions from fossil-fuel systems and minimizing indirect emissions through energy efficiency improvements. Efforts to decarbonize increasingly focus on electrifying heating, integrating renewable energy, and adopting advanced technologies that can greatly lower a building’s carbon footprint.


Pathways to Decarbonize HVAC Systems:


  1. Electrification of HVAC: Transitioning from gas boilers and furnaces to electric heat pumps can significantly cut direct emissions from fossil fuels. Paired with renewable energy sources, electric heat pumps further reduce both emissions and operating costs.


  2. Use of Renewable Energy: Integrating renewable sources like solar panels and wind power with HVAC systems reduces reliance on grid electricity. When HVAC systems are powered by renewable energy, buildings can move closer to achieving net-zero emissions.


  3. District Heating and Cooling Systems: Serving multiple buildings from a centralized plant, district heating and cooling systems dramatically reduce energy consumption and emissions. These systems are highly effective in urban areas and industrial complexes, where centralized efficiency can impact entire communities.


  4. Energy Storage and Peak Shaving: Battery storage systems allow buildings to store off-peak energy for later use, lowering demand on the grid and reducing costs. This approach also decreases the carbon footprint by reducing peak-time energy consumption.


  5. Low-Pressure, High Dust Loading Filtration: Low-pressure, high dust-loading filtration technology enables HVAC systems to maintain excellent indoor air quality without increasing energy consumption. By reducing strain on HVAC systems, these filters help optimize energy usage, creating a balanced, low-energy approach to superior indoor air quality. In high-traffic and sensitive environments, this filtration technology promotes sustainability and health but also contributes to lower peak energy demand and overall kWh usage.


Smart HVAC through Real-Time Data and Technology

Smart HVAC systems leverage IoT sensors, AI, and machine learning to enhance building management by providing real-time insights into temperature, occupancy, and indoor air quality (IAQ). IoT sensors enable systems to adjust settings based on occupancy and external conditions, optimizing comfort and reducing energy use. For example, unoccupied zones can automatically receive less heating or cooling, saving energy without sacrificing comfort.


Predictive maintenance is another key feature. It uses data to anticipate and address minor issues before they escalate, reducing repair costs and extending system lifespan. Machine learning further enhances efficiency by learning from usage patterns to optimize settings dynamically, reducing overall energy consumption. IAQ sensors adjust ventilation in response to pollutants, ensuring healthy indoor air, especially in high-occupancy environments like schools and hospitals.


This adaptive functionality not only lowers operational costs and peak energy demand but also supports sustainability goals by reducing carbon footprints. Smart HVAC systems offer continuous optimization, making buildings more resilient, efficient, and environmentally responsible.


Economic Incentives for Sustainable HVAC Systems

The economic benefits of sustainable HVAC upgrades are extensive. Although energy-efficient technology often requires an initial investment, the long-term savings in reduced energy bills can be substantial. Additionally, building owners may qualify for government incentives, grants, and rebates aimed at supporting energy-efficient retrofits. These financial incentives help offset initial costs, making sustainable HVAC upgrades more financially accessible.


Examples of Government Incentives

These incentives make sustainable HVAC systems more affordable and accessible, encouraging widespread adoption and supporting overall energy efficiency and decarbonization efforts.


Future-Proofing Buildings with Sustainable HVAC Solutions

The global transition to net-zero emissions by 2050 hinges on making our built environments sustainable and resilient. HVAC systems, with their substantial energy demands and carbon impact, are essential to this transformation. By embracing energy-efficient and decarbonized HVAC technologies, we can future-proof buildings against rising energy costs, regulatory changes, and environmental pressures.


This shift goes beyond simply improving IAQ or reducing energy bills; it’s about creating spaces where sustainability, health, and operational efficiency coexist. Clean, breathable air is not just a perk—it’s a necessity for well-being and productivity. Likewise, efficient, low-emission buildings are essential for a low-carbon economy.



The future of HVAC is evolving in a way that aligns energy efficiency, decarbonization, and indoor air quality as complementary goals. This shift challenges the traditional trade-offs between these objectives, proving that clean air and efficient energy use can coexist without compromise. HVAC systems of the future will be integrated, smart, and sustainable, paving the way for buildings that are not only more environmentally responsible but also healthier and more enjoyable to inhabit.


With ongoing innovations in HVAC technology, we are reaching a point where buildings can actively contribute to sustainability and public health, setting a new standard for what it means to operate a truly green building. By adopting these advanced systems, we are moving toward a reality where indoor spaces can maintain optimal air quality, reduce energy waste, and significantly cut emissions, creating a cleaner, more sustainable world.

Writer's pictureJennifer Crowley
Jul 28, 2023

Indoor Air Quality (IAQ) in Schools: Student Health and Performance

rear room view of an elementary classroom with various student's hands raised and the female teacher blurred at the front of the classroom
Students exposed to poor Indoor Air Quality may experience difficulty concentrating, fatigue, and a decline in productivity and overall well-being.

Indoor air quality (IAQ) is a critical yet often overlooked aspect of educational environments. The quality of air inside schools has a direct impact on student health and academic performance. In this blog, we will explore the significance of IAQ in schools and how it influences students’ well-being and learning outcomes.


To comprehend the importance of IAQ, it’s crucial to understand its components. IAQ refers to the condition of the air within buildings, including its purity, temperature, humidity, and ventilation.


Sources of Indoor Air Pollution in Schools

Sources of indoor air pollution in schools can vary, but here are some common ones:

  1. Building Materials: Some building materials used in schools, such as certain types of paint, adhesives, and flooring materials, can emit volatile organic compounds (VOCs) that contribute to indoor air pollution

  2. Cleaning Products: Cleaning chemicals, including disinfectants, floor cleaners, and aerosol sprays, often contain harmful chemicals that can release fumes and particles into the air, affecting indoor air quality.

  3. HVAC Systems: Poorly maintained heating, ventilation, and air conditioning (HVAC) systems can accumulate dust, mould, and other contaminants, which are then circulated throughout the building, compromising air quality.

  4. Mould and Moisture: Moisture problems, such as leaks or high humidity levels, can lead to the growth of mould and mildew. These can release spores and mycotoxins into the air, posing health risks.

  5. Pests and Pest Control: The presence of pests like rodents and insects in schools can introduce allergens and contaminants. The use of pesticides and insecticides for pest control can also contribute to indoor air pollution.

  6. Outdoor Air Pollution: Pollutants from outdoor sources, such as vehicle emissions and industrial activities, can infiltrate schools through poorly sealed windows, doors, or ventilation systems, compromising indoor air quality.

  7. Combustion Sources: Schools with combustion appliances, such as furnaces, boilers, or stoves, can emit pollutants such as carbon monoxide (CO), nitrogen dioxide (NO2), and particulate matter, which can be harmful when not adequately vented.

  8. Personal Care Products: Students and staff using personal care products, such as perfumes, colognes, and hair sprays, can contribute to indoor air pollution by releasing VOCs.

  9. Classroom Supplies: Various classroom supplies, including art materials, science lab chemicals, and glues, may contain hazardous substances that can release fumes or particles when used.

  10. Outdoor Contaminants: Pollen, allergens, and pollutants brought in from outdoors on clothing, shoes, or through open doors and windows can contribute to indoor air pollution.


It’s essential for schools to identify and mitigate these sources of indoor air pollution through adequate ventilation, regular maintenance, proper cleaning protocols, and the use of low-emission materials and products.


Impact of Poor IAQ on Students

Graphic illustration showcasing the various IAQ elements that affect Children vs Adults
Illnesses caused by poor IAQ have resulted in more sick days, from school, due to respiratory-related health problems.

Poor IAQ can have severe consequences for student health. It contributes to respiratory issues like asthma and allergies, increases the risk of infections and illnesses, and hampers cognitive function. Students exposed to poor IAQ may experience difficulty concentrating, fatigue, and a decline in overall well-being.


Student Health

According to the EPA, the term “sick building syndrome” (SBS) describes situations in which building occupants experience acute health and comfort effects that appear to be linked to time spent in a building, but no specific illness or cause can be identified.


Sick building syndrome has been reported by students in schools with poor IAQ. It is a condition that impacts employees or students that spend a lot of time indoors and is caused by unhealthy or stressful factors, i.e. poor ventilation. Illnesses caused by poor IAQ have resulted in more sick days, from school, due to respiratory-related health problems.


Cognitive Development and Academic Performance

Lack of adequate ventilation has been associated with poor cognitive development, especially in primary school age groups. An experiment was conducted through a Texas school district to improve the air quality condition in schools, which determined that IAQ improvements resulted in improved standardized test performance.


In another experiment, the average ventilation improvement project improved math and reading scores by 0.07 standard deviations (SDS) and 0.11 SDS, increasing the probability of passing these tests by 2–3%.


Increased Risks of Asthma and Respiratory Issues

Respiratory problems such as asthma are also aggravated due to air pollution in schools. A study has shown the possibility of reducing asthma incidents from 16% to 13% among children by simply applying filters for PM 2.5 in the classrooms.

Other respiratory health effects include:

  1. Coughing

  2. Difficulty breathing

  3. Airway inflammation & irritation

  4. Irregular heartbeat

  5. Lung damage


Simple Solutions to Help Manage Indoor Air Quality in School Classrooms


Mechanical Ventilation

Mechanical ventilation uses ducts and fans to draw in and distribute fresh air, and can even exhaust air from specific areas. In schools, mechanical ventilation uses HVAC systems or unit ventilators. To further enhance ventilation levels, air purification systems can be installed within existing ventilation systems or unit ventilators to achieve better air quality and reduce indoor air pollution levels.


Natural Ventilation

Simply opening a window or door encourages better airflow within an enclosed room. A study completed in 2017 proves a significant improvement in IAQ, specifically CO2 levels in a room with a group of 4-6 persons, by simply opening a window.

Illustration of how cross ventilation works, pulling air in from an open window and ventilating the rooms air through another open window
Cross ventilation allows a breeze to enter, flow through and exit within an enclosed area.

Additionally, cross ventilation is a highly effective method of promoting good airflow; Allowing a breeze to enter, flow through and exit within an enclosed area. This ventilation method encourages continuous airflow by pulling air from openings on one side of a building and through to the other.



Regular Cleaning & Dusting

Preventing any buildup of animal dander, dust mite matter, and pollen can improve indoor air quality. The American Lung Association recommends incorporating dusting into your regular cleaning routine, which can reduce the amount of dust and improve overall indoor air quality in your home.


Natural Cleaning Products

Substitute bi-products with natural-based products for cleaning agents to reduce indoor VOCs. A study conducted in Brisbane, Australia, in over 25 primary schools – to identify the VOCs’ sources – deduced that chemical-based cleaning products alone caused 41% of indoor VOCs. The synthetic fragrances found in cleaning and maintenance products contribute to air contamination.


Building Design 

The design of school and childcare facilities can contribute to minimizing children’s exposure to air pollution while onsite. This may entail locating the most frequented rooms or areas as far away from road traffic as possible, shielding the playground behind buildings, walls or green infrastructure (i.e. using plants), and allowing natural ventilation patterns that promote pollutant dispersion. Green infrastructure can filter some air pollutants and alter the airflow — thus changing pollution concentrations in local microenvironments.

Explore expert insights, stay up to date with industry events, and gain a deeper understanding of the cutting-edge developments that are revolutionizing the indoor air quality landscape within Blade Air's comprehensive Insights Hub.

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